Siemens CP 1515 - Manual (Page 289)

Industrial Ethernet Wireless LAN RLM Manager, CP 1515 Manager
C79000-G8976-C171-01
289
With the spanning tree algorithm, all bridges on the LAN exchange
special configuration messages that allow them to:
n Elect a single bridge among all bridges in the connected LAN
segments to be the root bridge.
n Calculate the distance of the shortest path to the Root Bridge.
n Elect a ‘Designated Bridge’ in each LAN segment that will
forward packets between that LAN segment and the Root
Bridge.
Select a ‘Root Port’ among all ports of the bridge unit.
The spanning tree algorithm enables bridges to calculate a loop-free
subset of the LAN topology (a tree) that provides the most efficient
level of connectivity between every pair of physically connected Local
Area Network segments.
If the ‘shortest data path’ fails, (for example as a result of a physical
breakdown), the Spanning Tree will automatically rebuild the topology
within the confines of the available bridged LAN components.
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The station address is a unique identification designator stored in
each SIMATIC NET IWL PC Card and Radio Link Module. The
addressing system used for station addresses conforms to the
universal MAC addressing convention. The station address is a 12
digit, alphanumeric code, arranged as 6 digit pairs of hexadecimal
numbers (see also ““MAC Address””)